Inside our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts on an AR can actually affect accuracy – like free-floating handguards, barrels, bolts, bolt carriers?” He wanted an honest, well-informed answer, not merely sales pitches. Robert Whitley posted an extremely comprehensive answer to this inquiry, based on his experience building and testing a large number of AR-15 complete upper. Robert runs AR-X Enterprises, which produces match-grade uppers for High Power competitors, tactical shooters, and varminters.
There are a variety of things which can be done with an AR to enhance consistent accuracy, and i also utilize the words “consistent accuracy” because consistency is an integral part of it (i.e. a good amount of guns will offer several great 5-shot groups, but won’t do a very good 10- or 20-shot groups, plus some guns will shoot great one day instead of so great on others).
Listed here are 14 key things we believe are essential to accuracy.
1. Great Barrel: You’ll want a premium match-grade barrel, well-machined with a good crown along with a match-type chambering, true on the bore and well cut. The extension threads also must be cut true towards the bore, with everything else true and in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The normal AR upper receiver was made for any lightweight carry rifle plus they stripped each of the metal they could off it to really make it light to hold (that is advantageous for that military). The net result are upper receivers which can be so thin you are able to flex them your bare hands. These flexible uppers are “strong enough” for general use, however are not suitable for accuracy. Accuracy improves having a more rigid upper receiver.
3. True Receiver Face: We’ve learned that truing the receiver face is valuable. Some may argue this time yet it is always best to keep everything related to the barrel and the bore in complete alignment using the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You need to Loctite or glue the barrel extension to the upper receiver. This holds it in place all the way front to back into the upper receiver. Otherwise if there is any play (there typically is) it merely hangs on the face of your upper receiver completely reliant on your face of your upper receiver because the sole source of support for your barrel in contrast to being made more a fundamental element of the upper receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You will want gas block that fails to impose pointed stress about the barrel. Clamp-on types that grab entirely round the barrel are fantastic. The blocks which are pinned up with tapered pins that wedge from the barrel or perhaps the slip on sort of block with set screws that push up from underneath (or directly on the barrel) can deform the bore inside of the barrel and can wreck the accuracy of an otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and I emphasize the phrase rigid) really is important. There are lots of kinds of free-float handguards as well as a free-float handguard is, in and of itself, an enormous improvement over a non-free-float setup, but best is actually a rigid set-up. Some of the ones in the marketplace are small diameter, thin and flexible and in case you are shooting off any type of rest, bipod, front bag, etc., a rigid fore-end is better since ARs wish to jump, bounce and twist once you let an attempt go, since the carrier starts to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You desire some meat in the barrel. Between the upper receiver and also the gas block don’t go real thin by using a barrel (we like 1? diameter if it’s workable weight-wise). If you touch off a round and the bullet passes the gas port, the gas system immediately starts pressuring with a gas impulse which offers vibrations and stress about the barrel, especially in between the gas block back to the receiver. A heavier barrel here dampens that. Staying just a little heavier with barrel contour from the gas block area and to the muzzle is useful for the same reasons. ARs have a lot taking place if you touch off a round along with the gas system pressures up and the carrier starts moving (all just before the bullet exits the bore) so the more situations are made heavier and rigid to counteract that this better – within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You need a gas tube that runs freely through the barrel nut, from the front from the upper receiver, and through the gas key within the carrier. Make sure the gas tube is not impinged by any one of them, in order that it is not going to load the carrier inside a stressed orientation. You don’t want the gas tube bound up so that if the gas tube pressures up it immediately wants to transmit more force and impulse for the barrel than would normally occur. We sometimes spend a 63dexjpky of energy moving the gas block with gas tube on / off new build uppers and tweaking gas tubes to obtain proper clearance and alignment. Most gas tubes do need a little “tweaking” to obtain them right – factory tubes may work OK nevertheless they typically do not function optimally without hand-fitting.
9. Gas Port Tuning: You want to avoid over-porting the gas port. Being over-gassed helps make the gas system pressure up earlier and more aggressively. This causes more impulse, and increases forces and vibration affecting the very best end as well as the barrel. Tune the gas port to provide the level of pressure needed to function properly and adequately but no longer.
10. Front/Back Bolt Play: If accuracy is definitely the game, don’t leave plenty of front/back bolt play (ensure that is stays .003? but at most .005?). We’ve seen factory rifles run .012? to .015? play, which is OK if you have to leave room for dirt and grime in the military application. However, that volume of play is not really well suited for a higher-accuracy AR build. A great deal of front/back bolt play allows rounds to get hammered into the chamber and re-formed in a non-consistent way, as they are loaded into the chamber.
11. Component Quality: Use good parts coming from a reputable source and become wary of “gun show specials”. All parts usually are not the same. Some are great, some are certainly not so great, and some aftermarket parts are simply just bad. Don’t be afraid to utilize mil-spec-type carriers; by and large they can be excellent for an accuracy build. Also, keep in mind that even though a carrier says “National Match” or anything else on it does not always mean it’s any better. Be wary of chrome-plated parts as the chrome plating can transform the various components dimensionally and will also ensure it is difficult to do hand-fitting for fit and performance.
12. Upper to reduce Fit: An excellent upper/lower fit is effective. For fast and dirty fit enhancement, an Accu-Wedge inside the rear helps a great deal. The supreme option would be to sleep the top to your specific lower in order that the upper and lower, when together, are definitely more like one integral unit. For your upper receivers we produce, we attempt to have the specs as near as we can, yet still fit the different lowers in the market place.
13. Muzzle Attachments: Don’t screw the muzzle (literally). Leave the maximum amount of metal around the barrel with the muzzle as possible. People love to thread the muzzle for a flash hider, suppressor, muzzle brake, or some other attachment, but when you truly desire accuracy, leave the maximum amount of metal since you can there. And, if you have something which screws on, set it up so that it may be put on and get it stay there without putting plenty of torque and stress upon it right in which the bullet exits the bore. If you are going to thread the conclusion of your barrel, allow it to be concentric using the bore and be sure whatever you screw on the website is as well. For all those muzzle attachments, also ensure that the holes whereby the bullet passes through are dead true to the bore. Many aftermarket screw-on situations are not so good that way. Something that vents gas should vent symmetrically (i.e. if it vents left, it will vent equally right, and likewise, whether it vents up, it ought to vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo is actually a whole story by itself, but loads that are too hot typically shoot poorly in best AR-15 barrel. If you need accuracy out of an AR-15, avoid overly hot loads. Shown here are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all virtually had a similar features and things done to them as explained in this article, and so they all shot great.